Summary of Changes in AOCI by Component (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Equity [Abstract]
Currency translation adjustment, Beginning Balance		$ (3,191)		$ (2,323)
Currency translation adjustment, Other comprehensive income before reclassifications		(247)		(1,094)
Currency translation adjustment, Amounts reclassified from AOCI		0		0
Currency translation adjustment, Net other comprehensive (loss) income		(247)		(1,094)		$ (1,332)
Currency translation adjustment, Distribution to Baxalta				226
Currency translation adjustment, Ending Balance		(3,438)		(3,191)		(2,323)
Pension and other employee benefit, Beginning Balance		(1,064)		(1,427)
Pension and other employee benefit, Other comprehensive income before reclassifications		(191)		45
Pension and other employee benefit, Amounts reclassified from AOCI	[1]	94		120
Pension and other employee benefit, Net other comprehensive (loss) income		(97)		165		(400)
Pension and other employee benefit, Distribution to Baxalta				198
Pension and other employee benefit, Ending Balance		(1,161)		(1,064)		(1,427)
Hedging activities, Beginning Balance		7		34		10
Hedging activities, Other comprehensive income before reclassifications		1		46
Hedging activities, Amounts reclassified from AOCI		(5)	[1]	(31)	[1]	(8)
Hedging activities, Net other comprehensive (loss) income		(4)		15		24
Hedging activities, Distribution to Baxalta				(42)
Hedging activities, Ending Balance		3		7		34
Available-for-sale securities, Beginning Balance		4,472		66
Available-for-sale securities, Other comprehensive income before reclassifications		104		4,461
Available-for-sale securities, Amounts reclassified from AOCI		(4,536)		(23)
Available-for-sale securities, Net other comprehensive (loss) income		(4,432)		4,438		34
Available-for-sale securities, Distribution to Baxalta				(32)
Available-for-sale securities, Ending Balance		40		4,472		66
Total, Beginning Balance		224		(3,650)
Total, Other comprehensive income before reclassifications		(333)		3,458
Total, Amounts reclassified from AOCI	[1]	(4,447)		66
Total, Net other comprehensive (loss) income		(4,780)		3,524		(1,674)
Total, Distribution to Baxalta				350
Total, Ending Balance		$ (4,556)		$ 224		$ (3,650)

[1] Amounts in parentheses indicate reductions to net income.